Automatic volume control for keyboard operated musical instruments



1950 E. w. SWEDIEN AUTOMATIC VOLUME CONTROL FOR KEYBOARD OPERATED MUSICAL INSTRUMENTS Filed April 26, 1948 37;; I N V E N T O R W ELLSWORTH W.SWEDiEN Y K 5 Mo FIG.

ATTORNEYS Patented Feb. 14, 1950 AUTOMATIC VOLUME CONTROL FOR KEY- BOARD OPERATED MENTS MUSICAL INSTRU- Ellsworth W. Swedien, Minneapolis, Minn., as-

signor to Patent Management, Incorporated, Minneapolis, Minn, a corporation of Minnesota Application April 26, 1948, Serial No. 23,373

14 Claims.

My invention relates to switch actions for electrical musical instruments and has for an object to produce an action in which the usual key thump is eliminated.

Another object of the invention resides in providing an action in which the volume of the tones of the instrument are gradually brought up to normal as the keys of the instrument are depressed.

A still further object of the invention resides in providing an action in which the rate of variation in tone volume can be manually controlled.

An object of the invention resides in providing an action in which the volume of the tones can be controlled by the extent of depression of the keys.

Another object of the invention resides in providing a musical instrument in which the noise level is reduced to a minimum.

A still further object of the invention resides in providin the action with a number of key actuated switches each having a movable contact and in further providing a number of fixed contacts having impedances or resistors connected therebetween and forming in combination an attenuator.

Another object of the invention resides in utilizing a single attenuator common to a number of switches.

A still further object of the invention resides in providing an elongated support and in arranging along the same a number of elongated contacts and in further arranging a number of the movable contacts of the switches adjacent the fixed contacts and each adapted to independently engage the fixed contacts.

Another object of the invention resides in the specific construction of the switches and the actuating mechanism therefore.

A still further object of the invention resides in providing the generators of the instrument with separate output connections and a common return and in connecting the switch blades of said switches to said output connections and one end of said attenuator to said common return, and in further energizing the sound producing device of the instrument from the output of the attenuator.

Other objects of the invention reside in the novel combination and arrangement of parts and in the details of construction hereinafter illustrated and/or described.

In the drawings:

Fig. l is a wiring diagram of a portion of a musical instrument illustrating an embodiment of my invention.

Fig. 2 is a cross sectional view taken through the key board and switch action of the invention.

Fig. 3 is a fragmentary longitudinal sectional view of a portion of the structure illustrating Fig. 2 and taken on line 3-3 of Fig. 2.

Fig. 4 is a perspective view of one of the movable switch blades of the switch action.

Fig. 5 is a sectional detail view of a portion of the attenuator taken on line 5--5 of Fig. 2.

In Figs. 2 and 3 I have shown a portion of a musical instrument which includes a key board Ill associated with a case ll having a vertical panel l2. The key board [0 includes a fulcrum bar it which is constructed with an inverted v-shaped surface 14 on which the various keys i5 and it rest. These keys are pivoted to the fulcrum bar l3 by means of pins I! which extend through holes l8 in said keys and which are driven into the bar 13. The keys l5 and I6 have arms is extending rearwardly from the fulcrum bar l3 and which operate the key action of the invention. I

The key action of the invention utilizes a number of attenuators, one of which is indicated at 2| in the drawings. This attenuator consists of an elongated support 22 preferably rectangular in cross section and having a forward surface 23, a rearward surface '24, an upper surface 25 and a lower surface 26. The support 22 is attached to a pusher mounting 21 by means of a bracket 28. This bracket is in the form of an angle having one leg 29 underlying the lower surface 26 of the support 22 and secured thereto by means of screws 3|. The said bracket has another leg 32 which overlies the mounting 21 and is secured thereto by means of screws 33. The mounting 2i is supported on a longitudinally extending shelf 34 by means of a bracket 35 which is similar to the bracket 28 and which is used in the same manner. Shelf 34 is supported by the case H and extends up to the panel l2.

The forward surface 23 of the support 22 is constructed with a number of spaced parallel grooves 36 which extend throughout the extent of the said support. In these grooves are mounted a number of bare wires 3! which are bent over the ends of the said support and are secured in position in spaced relation at the ends of the support by means of clamp bars, one of which is illustrated at 38 in Fig. 3. Two screws 89 extending through this clamp bar are screwed into the support 22 and hold the wires 31 rigidly in position. These wires form a number of elongated spaced contacts. At the rear surface 24 of the support 22 is disposed a mounting strip 39 of insulating material which is held attached to the said support and in spaced relation to the surface 24 by means of screws 4| and spacer sleeves 42 surrounding said screws. Arranged on this mounting strip are a number of resistors 43 which are held attached thereto by bending the terminals 44 of said resistors over the edge of the said mounting strip. These resistors are conbe subsequently more fully described in connection with the wiring diagramnf Fig. 1.

For each key l and I6 is provided a switch for actuating the tone producing means controlled thereby. These switches have been indicated in Figs. 1 and 3 byithe referencecharacters 50a, 50b, 500, etc. The fixed contacts 3'! serve as the common fixed contacts of a group ""ductcr i? to a resistor 18.

4 ithesame. One end of the windingldis grounded through a conductor TE "while the other end of said winding is connected by means of a con- The other end of this resistoris connected to a switch 19 forming one of the switch elements of the stop switch of the said switch, each switch having a separate movable contact carried by a separate switch I blade. These switches being all of the same con struction, only the switch 5% and associated parts'will'be 'describ'edin detail. The switch'iiilb is best shownin Fig. 4 an'd'consistsof a'switch blade ticonstructed u'f resilientmaterial. This switch blade is U shape'din'fonnhaving spaced arms "t6 "and 41 with a curved connecting *portion 48 therebetween. "The arrn lfiis longer-than the'arm l'l *having'wbodyportion 49 at=the end of the same provided with two -holes 5l. This body portion overlies thesurface'ZE of the support'22 and-is'secure'd thereto-by'means of two screws 52 which extend through the holes 5! and are'screwe'd into the-support -22. The innermost end of the arm 4! *term'inates short of the surface 2-3-of thesupp'ort fi. Thisend of the arm has attached *to-it =a finger 53 constructed of wire and bent with two parallel reaches 54 and '55 having a -connecting portion 5'6 "therebetween. The two-reaches 5 and "55 ere-constructed. with outwardly projecting bends 5! which serve as contacts adapted to bearagainst the outermost surf-aces ofthe wires =3! which form the hired contacts'o'f the'attenuator. The "finger 53 may lee-solderedor otherwise-secured'to the inner end of the arm 4-1 and-- extends angularly therefrom, being substantia'lly parallel to the surface 23.

The switches of *the attenuator are operated in :the following manner. 1n the arm 41 of the switch bladeAfi is formed an enlargement 58. This -enlargement has a hole in the same which is adapted to receive a pin 6! formed on the uppermost-end of a -pusher Pusher 82 is guidedxfor verticalunovement ina bore-63 formed in :thepusher mounting 21. The said pusher has a headafi l whichiisadapted to engage and restLuponrthesinnermost end' ofthe arm 19 of the particularakey 5!:5 Joril 5 with whichthe switch operated,thereby tisiassociated and is of such length that whenthezcontact 'd'liis.in engagement with 7 one of .thezlowermostnontacts 371a, the :par-

ticularkeywith which itzis associated is in normal position. ".The'uppermost .surface fihof thepusher mounting i221 forms asstop for engagement with the arm -47 of switch :blade 45 -TWhiCh limits the movement cof tsaid contact :51. :to such :position. When the keysdfi and?! 6 taredepressedgthearms l9 are raised;vp11shers :62 .are "elevated and the switch blades limoued'upwardly. This causes the contacts 'fihto travel along the :wires :31 until theisaid contactsreacntheuppermost-of the said wires. shoulder fifl'nn the :pusher engages the underside :of the'pushe'r .mounting =2! and limits the .upwardtmovement :of the contacts 57.

The musical instrument with which the switch action isassociatedrcomprisesa number of generators of electrical oscillations, two of which have %been diagrammatically -indicated at 66 and 61. "These generators include rotors 68 and 69 which :have iron teeth 1| formed therein. The said rotors cooperate with core members "1-2 and 1*3 whi'ch have'windings 14 and mounted on mechanism of .theiinstrument. In like manner, one end of. the winding "I5 is grounded through ia conductor 8'l'while' the other end of said wind- .ing is connected through a conductor 82 with a resistor 83. This resistor in turn is connected toa switch s lwforming a switch element of the stop switch mechanism. In most musical instruments, it is customary to collectively control the actuation of the generators by means of one or more step switchmechanisms. -In "as much'as 'these'function'in the ordinary'manner, onlytwo switchelements thereof have beenshown, namely switches '19 and 84, though it"can bereadily-comprehended-that *as'many switch elements will be required as there are generators and keys and the-samewill be ganged together to produce the desired results inthe customary manner. Switch 78 is connected by means of a conductor 85 to the switch blade 45o'f'switch- 50a 'whileswitch 8 4 is connected -by--means of 'a =c'ondu'ctor 86 to the-switch blade 45 of switch 5%. Other generators not shown are conne'cted-to the other switches. The=various resistors 413; etc.,"are connected in series by means (if *a number =01 "conductors 87. The points of connection between these resistors are connected by means of *conductors -88 to the wires 3-1 the opposite ends or" said wires being open. The "first three of the wires 37 which are denoted by the reference numerals (We are connected together and to the conductor fida. "Thisconductcrisin turngrounded. 'The en'd-resistor 43:1: 'isconnected by means o'f-a-conductQr BS to 'the 'grid '91 of a thermionic tube 9-2 forming part of "an amplifier indicated diagrammatically at 93 and forming part-of a sound producing decice indicated in its entirety by the reference'numeral This amplifier feeds a loud speaker 95. The grid return of the tube" 92 a is "connected by means of a conductor 96 to ground. While Ihave shown in Fig. 1 the actual number of contacts =31 employed in an electrical-instrument now in-use, a lesser number of contacts have'ibeen shown in Figs. 2, 3 and 4 to simplify the illustration "of the invention. It can be readily understood however, that any number of contacts "31' mast be used .over which the movable contactst'i can be made totravel. The operation of the invention is -:as follows:

. In normal position the switch blades 45 are in "the: position shown inzfi ig. 12 with :contacts 51 :engaging tone rof ithe'fl'owermost contacts 311:. This :places "the conductors -85, I 86, e'tc., :at ground potential. Sin'ce' these-zsw itch :blades :are connected toone.end of the-windings T4, '75, etc., and the other endswo'f "these windings are grounded through :the conductors lfi and 8 I, the said windings are completely shorted out and no -=energy-=is transferred from the said windings to the attenuator. ".Thus the =noise level is greatly lowered "with the present'invention. one of the switches 50a, etc., is-actu'ated,*the contact 5 thereof successively engagesthe contacts 31. This shifts the Said. contact-along the contacts 3? *or 'the attenuator 1H and increases the voltage derived from the said attenuator and utilized for energizing the =amplmer 93. 'When the contact '5? reaches the uppermost contact 37:0, the

down, the volume of the tones produced by the instrument can be varied. Also the rate of change of volume can be manually varied by the rapidity by which the keys are depressed.

The advantages of the invention are manifest. With my invention key thump and blasting are completely eliminated. At the same time, the noise level is lowered to a minimum. Since the generators are shorted out when the keys are in normal position, no transfer of energy from the same to the system occurs. With my -in-' vention there is no opportunity for transfer of energy through capacity of juxtaposed components. By means of the particular construction employed, uniform pressure is exerted on the contacts throughout the movement of the same. By utilizing a finger constructed of parallel reaches of wire, two contacts are furnished for each switch blade thus insuring the positive actuation of the switches. With my invention the support for the attenuator carries all of the various parts of the same thus permitting of independent manufacture of the attenuator and subsequent assembly of the same as a unit in the instrument.

Changes in the specific form of my invention, as herein described, may be made within the scope of what is claimed without departing from the spirit of my invention.

Having described my invention, what I claim as new and desire to protect by Letters Patent is:

1. In a switch action for musical instruments, an elongated support, a plurality of spaced juxtaposed grooves in a face of said support, a number of key actuated switches including a number of elongated contacts disposed in said grooves and having contact portions disposed in a common surface, a plurality of switch blades having movable contacts movable substantially in said surface and across said elongated contacts to successively make contact therewith and impedances between certain of said contacts.

2. In a switch action for musical instruments, an elongated support, a plurality of spaced juxtaposed grooves in a face of said support, a number of key actuated switches including a number of elongated contact wires in said grooves and having exposed edges arranged in common surface, a plurality of switch blades having movable contacts substantially in said surface and across said elongated contacts to successively make contact therewith and impedances between certain of said contacts.

3. In a switch action for musical instruments, an elongated support, having two oppositely facing surfaces, a plurality of key actuated switches including a number of fixed elongated contacts arranged in spaced juxtaposed relation along one of said surfaces, a plurality of switch blades each adapted to successively make contact with said contacts and resistors disposed on the other surface of said support and connected between said contacts.

4. In a switch action for musical instruments, an elongated support rectangular in cross section and having two oppositely facing surfaces with intermediate surfaces therebetween, a plurality of key actuated switches including a number of fixed elongated contacts arranged in spaced juxtaposed parallel relation along one of said oppositely facing surfaces, a plurality of switch blades mounted on one of said intermediate surfaces and having movable contacts adapted to successively make contact with said fixed contacts, resistors overlying the other of said opposed surfaces and connected between said fixed contacts and a mounting for said support at tached to the other of said intermediate surfaces.

5. In a switch action for musical instruments, an elongated support rectangular in cross section and having two oppositely facing surfaces with intermediate surfaces therebetween, a plurality of key actuated switches including a number of fixed elongated contacts arranged in spaced juxtaposed parallel relation along one of said oppositely facing surfaces, a plurality of switch blades mounted on one of said intermediate surfaces and having movable contacts adapted to successively make contact with said fixed contacts and resistors overlying the other of said opposed surfaces and connected between said fixed contacts.

. 6. In a switch action for musical instruments, an elongated support, a plurality of key actuated switches including a number of fixed elongated contacts arranged in spaced juxtaposed relation along said support, a plurality of switch blades each U-shaped in form and having an arm attached to said support and extending away from said support and another arm issuing from said first arm and extending toward said support, a finger on the end of said second named arm and extending angularly therefrom, a contact on said finger for successively engaging said fixed contacts, a pusher for each switch adapted to engage the second arm of each switch and impedances between said contacts.

7. In a switch action for musical instruments, an elongated support, having a planiform surface, a plurality of key actuated switches including a number of fixed elongated contacts arranged in spaced juxtaposed relation along said surface, a, plurality of flexible U-shaped switch blades each comprising an arm extending outwardly from said surface and another arm issuing from said first arm and extending toward said surface, a finger on the end of said second arm and extending substantially in the direction of extent of said surface, a contact on said finger for successively engaging said fixed contacts, a pusher for each switch adapted to engage the second named arm thereof, guide means for guiding each pusher for movement in a direction substantially parallel to said surface and impedances between said contacts.

8. In a switch action for musical instruments, an elongated support, rectangular in cross section and having two oppositely facing surfaces with intermediate surfaces therebetween, a plurality of key actuated switches including a number of fixed elongated contacts arranged in spaced juxtaposed parallel relation along one of said oppositely facing surfaces, a plurality of switch blades mounted on one of said intermediate surfaces and having movable contacts adapted to successively make contact with said fixed contacts, resistors overlying the other of said opposed surfaces and connected between said fixed contacts, an elongated mounting disposed adjacent said elongated support attaching means between said elongated support attached to the other of said intermediate surfaces and to said mounting guides in said mounting and a plurality of pushers slidably mounted in said guides and adapted to engage said second named arms to move the contacts thereof in the plane of said fixed contacts.

9. In a switch action for musical instruments including generators of electrical oscillations each having an output connection and a common return, a key corresponding with each of said g" "craters a sound producin devise new ice nut element and a return oonnectedto said o men return, :said switch action Loom- Pris-ins. an att nuator. hav n a movable contact adapted to be connected to the output connection of one .of said. generators and operated. bythe k y cor-responding therewith, one. end of said attenuator beingconnected to said common re,- turn and the other end ofsaid attenuator being connected to said input element, said. movable contact being at the return end of said attcnue ator-tvhen its key is in normal position.

10. in a switch action for musical instruments including generators of electrical oscillations each having an output connection and a. common return, a key corresponding with each of. said generators, a sound producing device, Said switch action comprising anaattenuator tracings. movable contact adapted to be connected to the output connection of' one of said generatorsand operated by the key corresponding therewith, one end of said attenuator being connected to saidcommon return, the voltage across said attenuator serving to energize said sound producing device, said movable contact being-at there turn end of said attenuator when its key is in normal position.

1 1. In a switch action for musical instruments including a pluralityof generators of electrical oscillations, each having an output COIIll-EOtiOfl-yand a common return a key correspondin-g with each of said generators and a sound producing device, said switch action comprising an attenu ator including a number of fixed contacts and resistors tnerebetween, switch blades operated by certain of said keys and adapted toindependently make contact-with said; fixed contacts. one end of said attenuator beingconnectedto said return, the output of said attenuator sewing to energize said sound producing device.

12. In a switch action for musical instruments including a =pluralityof generators of electrica'i oscillations, each having an out-put connection and a common return, a keycorresponding with each of said generators-and asound producing device, said switch action comprising a, single; attenuator for all of saidsound producingjdevioes; in the form of a potentiometerhaving a plurality of: movable contacts corresponding in number :to said keys, conducting means between one end of said potentiometer and said return, t h r end of said potentiometer servin to energize said output, device, conducting means between said movable contacts and said output connections and connectingmeans betweenxeachkey and one otsaidznovable contacts for moving said contact upon depression of the .key..

In a-switch-a-ction for musical instruments including: av generator of electrical oscillation havin an output. connection and a returnconnection, a key corresponding with said generator and a. sound producingv device, said, switch action comprising an attenuator in the form of a potentiometer having a, movable contact, one end oi said potentiometer being connected to said return connect-ion and the, other end being connected to said sound producing device, said output connection being connected to said movable contact,..and connecting means between said key and; movable contact for moving said contact upon-depression of said key, said contact being in contact with the end of said potentiometer connected to said return when the key is in. normal imition.v

14., .In a switch action :for .rmisical. instruments including a. generator of electrical. oscillation having an output connection and a return connest-ion, a key corresponding with .said generator and. asound producing device, said switch action comprising an adjustable resistor, said resistor being; connected in series with; said generator-and sound producing device and adjusting means for adjusting the vaiue of the-resistance ofvsaid resistorin series with said generator and sound producing; device and operated by said key.

ELLSWORTH'W. SWEDIEN.

REFERENCES CITED The following references are of record in the file of, this patent:

UNITED STATES PATENTS 

